Apparatus for sensing photographic color films and for converting a sensed video image into a video signal is well known in the art. Since the development of relatively low cost, reliable solid state image sensors there has been considerable interest in the development of film video players for displaying color film images such as those present on color slides and color negatives on television monitors and receivers. Equipment has also been developed which contemplates the use of a photographic system including a printer with a film video player, wherein a film image is first displayed on a video monitor or receiver, a video image corresponding to only a portion of the film image is selectively displayed for composition purposes and an optical print of a portion of the film corresponding to the selected video image is made.
A primary reason for the interest in composing selected video images constituting a portion of a film image is that the resolution of the commonly used photographic film format is substantially greater than standard television resolution by factors of approximately four to ten times. As will be appreciated, the full available resolution of these film formats is not effectively used at normal magnification where the full frame image substantially fills the solid state image sensor so that the video image effectively just fills the display of a television monitor or receiver. The excess resolution available in these film formats can be advantageously utilized by providing a film video player with means such as zoom optics for selectively changing the magnification of the video image and thus the displayed image with respect to the film image. Since in its magnified form the video image and resultant display constitutes only a portion of the film frame image, it is desirable to be able to effect relative vertical and horizontal translation between the film image and the video image. More advanced composing or editing functions can be carried out where it is possible to effect relative rotation between the film image and the video image.
A common approach in the design of film video players of this type contemplates the use of fixed apparatus for mounting a slide or film negative presenting a film image and a fixed sensor spaced a distance therefrom along the optical axis of the system. Interposed between the fixed film image and fixed sensor is a multi-group variable focal length lens wherein one of the lens elements is movable axially along the optical axis to vary the focal length of the lens and thus provide a zoom capability. Multi-group variable focal length lenses of this type suffer the disadvantage that they are relatively expensive. Such multi-group variable focal length lenses normally require the driving of a plurality of substantially fixed cam surfaces to effect the zoom functions. The cam surfaces are necessarily chosen to meet normal conditions for a particular system and cannot readily be altered or adjusted to accommodate manufacturing or assembly variations in variables such as the focal length of a particular lens or the exact plane where a film image or a sensor are mounted or oriented in a particular player. Normally, attempts to eliminate variables of this nature which degradate the performance of a film video player can be accomplished only by expensive adjustment or customizing procedures which must be employed for each individual unit being manufactured. Thus, the production of film video players employing multi-group variable focal length lenses involves extreme expense in terms of both the cost of the components employed and the labor required for assembly and adjustment due to the necessity for an essentially customized installation.
In the common film video players employing multi-group variable focal length lens as described above, an additional problem frequently encountered is that during scan with a lens being positioned off the optical axis relative to a stationary image sensor and a stationary film image unacceptable vignetting of the video image results. This vignetting can to an extent be controlled by the design of the multi-group variable focal length lens or other system components. However, to provide a multi-group lens which has a full range of zoom and scan characteristics, appropriate clarity without vignetting, an adequate field of view and meets the various required characteristics of a system may be virtually impossible or at least inordinately expensive.
In film video player devices where the photographic film presenting the film image is moved horizontally and vertically to effect scan of the film image relative to the optical axis significant ancillary problems are encountered. Such movement of the film carrying the film image creates mechanical difficulties in effecting quick film change which is highly desirable or in some instances essential in equipment of this type. In particular, whether slides or film negatives are employed, a moving slide or film holder makes it difficult if not impossible under reasonable cost constraints to design mechanisms for rapid loading and unloading of slides, film strips or other film segments. At the very least the utilization of known, inexpensive and proven slide and film change equipment is obviated. Thus, it is highly advantageous in devices of this type that the photographic film be presented in a mounting assembly which remains stationary.
Film video player devices where the sensor may be moved horizontally and vertically for scan purposes and in some instances rotationally, have been employed in the art. There are, however, numerous mechanical complexities in effecting such motions while maintaining interconnections for the substantial circuitry which is required for transmitting a control signal for a solid state image sensor and for transmitting the video signals generated by a solid state sensor. Such known devices have not endeavored to approach the additional mechanical and electrical interconnect complexities which arise in a system where the sensor is required to carry out scanning functions in a plurality of perpendicularly displaced parallel planes as opposed to the known single plane of operation.